Btrfs: read from backup copy if csum fails with DIO

Commit Message

Josef Bacik June 7, 2010, 9:07 p.m. UTC

None

Patch

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index d999c53..78c0547 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -5494,6 +5494,7 @@  struct btrfs_dio_private {
 	u64 bytes;
 	u32 *csums;
 	void *private;
+	int mirror;
 };
 
 static void btrfs_endio_direct_read(struct bio *bio, int err)
@@ -5503,8 +5504,11 @@  static void btrfs_endio_direct_read(struct bio *bio, int err)
 	struct btrfs_dio_private *dip = bio->bi_private;
 	struct inode *inode = dip->inode;
 	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct bio *new_bio;
 	u64 start;
 	u32 *private = dip->csums;
+	int num_copies;
+	int ret;
 
 	start = dip->logical_offset;
 	do {
@@ -5528,7 +5532,7 @@  static void btrfs_endio_direct_read(struct bio *bio, int err)
 				      " %llu csum %u private %u\n",
 				      inode->i_ino, (unsigned long long)start,
 				      csum, *private);
-				err = -EIO;
+				goto failed;
 			}
 		}
 
@@ -5537,6 +5541,7 @@  static void btrfs_endio_direct_read(struct bio *bio, int err)
 		bvec++;
 	} while (bvec <= bvec_end);
 
+out:
 	unlock_extent(&BTRFS_I(inode)->io_tree, dip->logical_offset,
 		      dip->logical_offset + dip->bytes - 1, GFP_NOFS);
 	bio->bi_private = dip->private;
@@ -5544,6 +5549,40 @@  static void btrfs_endio_direct_read(struct bio *bio, int err)
 	kfree(dip->csums);
 	kfree(dip);
 	dio_end_io(bio, err);
+	return;
+failed:
+	num_copies = btrfs_num_copies(&root->fs_info->mapping_tree,
+				      dip->logical_offset, dip->bytes);
+	dip->mirror++;
+	if (dip->mirror > num_copies) {
+		err = -EIO;
+		goto out;
+	}
+
+	new_bio = bio_clone(bio, GFP_NOFS);
+	if (!new_bio) {
+		err = -EIO;
+		goto out;
+	}
+
+	new_bio->bi_end_io = btrfs_endio_direct_read;
+	new_bio->bi_private = dip;
+	new_bio->bi_size = dip->bytes;
+	new_bio->bi_sector = dip->disk_bytenr >> 9;
+
+	ret = btrfs_bio_wq_end_io(root->fs_info, new_bio, 0);
+	if (ret) {
+		bio_put(new_bio);
+		err = -EIO;
+		goto out;
+	}
+
+	ret = btrfs_map_bio(root, READ, new_bio, dip->mirror, 1);
+	if (ret) {
+		bio_put(new_bio);
+		err = -EIO;
+		goto out;
+	}
 }
 
 static void btrfs_endio_direct_write(struct bio *bio, int err)
@@ -5674,6 +5713,7 @@  static void btrfs_submit_direct(int rw, struct bio *bio, struct inode *inode,
 	dip->private = bio->bi_private;
 	dip->inode = inode;
 	dip->logical_offset = file_offset;
+	dip->mirror = 0;
 
 	start = dip->logical_offset;
 	dip->bytes = 0;